Stereoelectronic effects: a simple yet powerful tool to manipulate anion affinity

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry

Background:

• Designing effective anion receptors is crucial for various chemical applications.
• Stereoelectronic effects, particularly those involving ether configurations, have been underappreciated in receptor design.

Purpose of the Study:

• To investigate the impact of stereoelectronic effects on anion binding.
• To quantify the influence of ether substituent orientation on receptor-ligand interactions.

Main Methods:

• Synthesis of rigid diol-based anion receptors with varying ether configurations.
• Binding studies using tetrabutylammonium chloride in acetonitrile-d3.
• Infrared (IR) spectroscopy to analyze complex structures.

Main Results:

• The stereochemical configuration of a non-interacting ether moiety altered binding affinity by over two orders of magnitude.
• An equatorial ether orientation, featuring a favorable C-O dipole and intramolecular C-HOH hydrogen bond, enhanced binding.
• Axial ether orientation resulted in less favorable binding compared to the equatorial configuration.

Conclusions:

• Stereoelectronic effects, specifically the orientation of ether substituents, play a critical role in anion receptor selectivity and strength.
• The study highlights the importance of considering conformational and stereoelectronic factors in the rational design of novel anion receptors.
• Identified binding motifs provide insights into the specific interactions governing anion recognition.